$green = #02a774;
$yellow = #f5a100;
$bc = #e4e4e4;

// 一像素下边框
bottom-border-1px($color)
  position: relative
  border: none
  &:after
    content:''
    position: absolute
    left: 0
    bottom: 0
    width :100%
    height:1px
    background-color: $color
    transform:scaleY(0.5)

// 上边框一像素
top-border-1px($color)
  position: relative
  border: none
  &::before
    content:''
    position: absolute
    left: 0
    top: 0
    z-index: 200
    width :100%
    height:1px
    background-color: $color
    transform:scaleY(0.5)

// 一像素边框

@media only screen and (-webkit-device-pixel-ratio: 2)
  .border-1px
    &::before
      transform:scaleY(0.5)

@media only screen and (-webkit-device-pixel-ratio: 3)
  .border-1px
    &::before
      transform:scaleY(33.33%)

bg-image($url)
  background-image:url($url+"@2x.png")
  @media (-webkit-device-pixel-ratio: 3),(device-pixel-ratio: 3)
    background-image:url($url+"@3x.png")
